Rounded keel and more fairing work

 It took a couple of hours to knock the keel down to the specified radii.  I was a little hesitant since it is harder to put foam back on than it is to shave off.  But with reassurance from Ian Farrier (which was remarkable if for no other reason than he had just experienced a serious earthquake in New Zealand the same day I emailed him), I went ahead and rounded over the keel.  The logic is the soft radius reduces wetted area, making for a faster boat.  I was careful to knock it down along the entire length simultaneous so as to avoid an irregular keel line.  I used the cheese grater for rough cutting and the long board for final figuring.

Here is an interesting view from the stern looking forward along the keel.  I am really happy with the figure of the hull and keel.   I think there is pretty good symmetry, and the lines of the hull seem to flow nicely.  Now I get to make it ugly again!

And here is the next step in fairing prior to glassing.  We skimmed the surface with a slightly thin fairing putty (1.25 cups balloons per 150 mL mixed epoxy), and then scraped most off with a fairing batten (actually it was a piece of sail batten from our old fashioned monohull, I can't believe anyone still sails with a single hull!)  The result was the putty filled in the low areas between the remaining fairing stripes we discussed last post.  And the higher areas were left pretty much bare.  Once this cures we should be able to sand it smooth with minimal effort.  Assuming we didn't miss any low spots, we would then be able to move on to glass work.  However, I am still waffling between glassing or installing the access port plates first.  Stay tuned to see how this conundrum is resolved!

Fairing as the next olympic sport

 I spent the past couple days sanding off all of the fairing putty stripes we discussed in the previous post.  All the rumors about fairing a boat are true - it is tiring and makes me feel like I'm going to pass out.  Of course most physical activity makes me feel this way, that's why I sail!  Actually, the sanding went fairly  quickly (pardon the pun), it just felt like it would take forever.  In this shot, you will see that we rotated the hull onto its side to make the process a little easier.  I highly recommend cradles with interchangeable forms, it really made life easy here.  You might also notice that I am standing on the strongback to get better leverage while sanding.  We thought a lot about either clearing out one side of the boat house, or removing the strongback, so we could put the hull at floor level.  But in the end I found this worked okay.  Most of the time I can comfortably stand on the floor and sand, but sometimes it was useful to get a little higher.  And so far I haven't slipped off or broken any important parts of me.

 Here is an excellent picture of me in mid stroke.  Notice the fine form, arms fully extended, eyes on the destination, balding spot in full view!  More importantly, notice that I am in full battle gear with respirator and 100% dust cartridges, tyvek suit, and gloves (with nitrile gloves underneath).  This activity makes a lot of dust, and I really don't want my lungs full of this epoxy/microballoon dust.  And 8 hours of sanding with a long board tends to tear up your hands, so the gloves are a necessity.  I am using 3M marine fairing boards (this one is the rigid version) and sand paper.  They are a little shorter than recommended at only 30".  But they worked quite well and I didn't have to spend any time building a board.

 After I finished sanding the entire surface, we removed the forms in the cradles and set the hull keel-side up so I could round over the keel.  Hopefully this will be the only time we ever see these hulls in this orientation!  It took about a day to sand the entire hull, which is less time than I expected.  I expect it will take a week for my arms, back, and shoulders to recover.  If you notice the piece of pvc pipe sitting on the keel, it is my reference for the radius of the keel.

Here is a close up view of the hull after sanding the stripes off.  It's hard to capture the fairness of the hull in a photo, so trust me when I state that this hull is pretty darn fair.  There are a few spots that are a little low, and the high spots were sanded flush.  The highest remaining stripes are only about 1/32", and most of the stripes are completely gone.  Although tiring and quite the workout, I found this fairing process very satisfying.  Not only did I get a great upper body cardio workout, the hull looks like it was built in a mold.

Next we will fill in the low areas with a thin veneer of fairing putty and sand again.  Assuming that takes care of the initial fairing, we will then move on to laminating the exterior.

Stripes are in style

 In an attempt to inspire the fashion world, we decided to add stylish stripes to the hulls!  Okay, maybe not ... What we are doing is starting the initial fairing of the starboard hull.  To make the process a little less tedious, and to reduce the amount of expensive epoxy and microballoons ending up on the floor, we are applying stripes of fairing compound initially.  These stripes are approximately 1/4" wide and 1/4" tall, with either a triangular or rounded profile.  After they cure, we will pull out the long board and start sanding them down until they are nearly gone.  The remaining stripes show the low areas, which can be filled in the second pass, hence minimizing the amount of fairing compound required.

 Here is what the application of the fairing stripes looks like part way through the process.  Initially this was rather frustrating because the putty would peel of as it was applied.  After some adjustments to technique and putty mix, I found the right procedure and it progressed more quickly.  The key was to make the putty slightly wetter than putty for fillets.  I used a mix of 1.375 cups of balloons for every 150 mL of mixed epoxy (sorry for the mixed unit conventions).  A little wetter was better than a little drier.  I didn't care too much about sag since I am sanding it all off, just as long as it doesn't drip.  The whole process took about a day.

Here is the high-tech, custom modified, double-edged, and most importantly - yellow squeegee I used.  The triangular notches are separated by 2" with an inch on the outer edges.  This layout made it easy to keep the stripes fairly uniform, though uniformity is only a requirement in the most general sense.  I actually made a second squeegee with rounded notches, which also worked well.  The application procedure started with sanding and vacuuming the entire surface so the putty would adhere well.  Then I applied a thin layer (~1/8-1/4 inch) of fairing putty over an area of the hull.  In general, I tried to do sections spanning from the keel to the deck seam.  Then I scraped off most of the putty with this notched squeegee, leaving stripes of putty behind.  The removed putty was reapplied on the next section of hull.  When the putty starts to get dry, I found it easier to mix a new batch and combine the leftover slightly drier putty with the new.  Just be careful you don't mix the old putty with new if the old stuff is kicking.  If some of the stripes come off, or aren't quite perfect, no big deal, just as long as most stripes are good.  Next time I'll show the sanding process (assuming I can still move!)

Miscellaneous details

 We are finally nearing the end of the task list for the starboard hull prior to fairing and exterior lamination.  So here are a few last details.

We reinstalled the main deck hatch just like we did for the smaller access ports.  The intent is to provide a nice uniform hull shape for fairing.  The weights are there to hold the two halves together at the seam until the epoxy sets.  After initial fairing, we will recut the access hatches and ports.  We debated options for the main hatch.  One option is to build a custom flush hatch. The other option is to install a commercial hatch.  We finally decided to take the slightly easier route of installing Beckson hatches.  So after fairing, we will cut out the opening and install a flat plate to form a rim for the hatch.  We are going to install the hatch so it is close to flush, which should help keep a clean look.  The rim will also provide reinforcement and stiffening around the large hatch opening.

 I cut some foam panels for the hatch rims.  I am making rims for both the round access ports as well as the rectangular main deck hatch.  I decided to pre-glass the rim plates to help ensure they are flat. The main reason these commercial hatches leak is because the surface they are mounted to is not flat.  But the cold weather makes epoxy curing a challenge.  To help the chemistry cook, I assembled a shanty hutch out of scrap wood, boxes, foam, and towels.  I placed a space heater in the opening of the hutch and set the thermostat to 65 F.   Then I let the foam-glass-epoxy sandwich simmer for a few hours under vacuum.

We cleaned up the stern seam.  It now looks fair and will blend in to the hull shape naturally.  We still have quite a lot of exterior prep work to do.  But it is good to see a nearly finished hull coming together.

Closing up the bow

The process of closing up the bow is similar to that for the stern.  The biggest difference is you can't really reach the bow on the inside, so it is not taped internally.  Rather, the edges are taped prior to covering the bow opening.

 Once the edges start to cure, and after all other inside work is complete (especially the bow pad eye), a pre-glassed plate is glued over the bow opening.  We used a thick putty made from cabosil (to prevent running) and microballoons (to fill all gaps).  We buttered both the hull edges and the plate with putty to ensure both were strongly adhered to the putty. Then we pressed the plate on and let the putty squeeze out.  I used a few screws to hold the plate in place until the epoxy set.  Note the scribbles on the outside of the plate to remind me there is still peel-ply on this surface.  Without the scribbles, it would be easy to forget to remove the peel-ply prior to exterior lamination.  The result would be rapid de-lamination, and a bad day.

Here is a view of the bow from the inside after gluing on the plate. Note the excess putty squeezing in around the seam.  It is not practical to clean it up or add tape.  I find it very difficult to leave it like this, but there aren't many options.  And this is the method Ian Farrier suggests in his building guide.  Being at the bow, it isn't noticeable from the access ports in any case, unless one tries to look for it.

The last step in closing up the bow is to reinstall the temporary access port in the bow deck.  Though difficult to see in the photo, I started by adding a glass epoxy skirt around the foam cut outs.  By letting the glass set up on the deck, it forms the proper shape to fit the inside contours.  Once set, I will use a thinner putty with extra cabosil to glue the skirt around the cut out to the inner hull.  Then the seam will be filled with putty for fairing.  The inside of this cut out will not be accessible so the skirt is the only option for adding inside reinforcement.  Unfortunately, the weather headed south (or more accurately north) with record setting cold. So final installation will have to wait for warmer days.

First hardware installed (temporarily)

We installed the first hardware, the pad eye on the bow, at least temporarily.  Since the pad eye is inaccessible once the bow is closed up, some type of fasteners have to be permanently installed now.  I didn't like the idea of installing bolts from the inside with the threaded ends sticking out.  I chose to make a thick backing plate with threaded holes so the bolts are installed on the outside and can be removed if needed.  This configuration also makes exterior fairing and glassing easier without protruding obstructions.  The bolts shown are only temporary to hold everything in place while the epoxy sets (see below).  In the final assembly, after paint, the pad eyes will be held in place with socket button head bolts for a more finished look.

 Here you can see the installed pad eye and its twin awaiting the port hull.  Note the heavy backing plate (much heavier than needed just for backing).  The backing plate is 3/8" 316 stainless steel.  The edges are all chamfered to make it easier to glass in place and also to reduce a weight a little.  I am not trying to make this the lightest F-82R around, but I did have to think about the options for this plate since it is somewhat heavy.  But I figure it is better to go heavy on this inaccessible component rather than cut open the finished hull to make repairs later.  All other backing plates will be 1/8" with no threads.

This is a shot of the backing plate on the inside of the bow, after the bow was closed up (see next post).  I started by match drilling the holes through the hull for the bolts and dry fit everything.  Then I made a thick putty with cabosil and microballoons to bed the backing plate.  This is important so the plate presses evenly over its entire contact area. Without the bedding, the plate would pinch the hull at a few points, which could crush the core and weaken the hardware attachment.  I held the plate in place with the bolts tight enough to squeeze out excess putty, but not too tight.  The bolts also helped keep epoxy out of the threads.  Once set, I added a layer of glass tape and epoxy to permanently hold the plate in place.  The chamfered edges helped the glass cover the plate more smoothly and securely.  Hopefully this plate will outlast the boat.